Great Auricular Nerve Block

CHAPTER

71 

Great Auricular Nerve Block The great auricular nerve (GAN) is the largest branch of the superficial cervical plexus (see Chapter 72, Fig. 72-1). The nerve arises mainly from the third cervical nerve (C3) with inconstant contributions from the second cervical nerve (C2). It provides cutaneous innervation to the periauricular region.1 The GAN wraps around the posterior border of the sternocleidomastoid muscle (SCM) and then courses superiorly and anteriorly, dividing into anterior and posterior branches. Because of its superficial location, the GAN can be damaged during surgical procedures in the neck. The nerves of the superficial cervical plexus lie deep to the platysma when first emerging from the plexus, but it lies superficial to the prevertebral fascia. The GAN lies superficial to the lateral border of the SCM and can be traced to the preauricular area or back to the superficial cervical plexus. The lesser occipital nerve has similar anatomy, except that it can be followed behind the ear. GAN block can be used to provide anesthesia for external ear surgeries.2,3 The average GAN diameter is 1.4 mm.4

SUGGESTED TECHNIQUE The GAN has a characteristic monofascicular or bifascicular appearance on ultrasound scans where it courses over the SCM. The GAN flattens in shape slightly as it lies over the SCM. The nerve becomes difficult to image at the lateral corner of the SCM. This point is about the level of the cricoid cartilage. Isolated GAN blocks are possible, but its large size and characteristic ultrasound appearance make the GAN a convenient way of identifying the position of the remainder of the superficial cervical plexus. Because the GAN is very superficial, an out-of-plane approach to GAN block is usually used with the nerve viewed in short axis. The GAN lies near the external jugular vein, so vascular puncture and minor bleeding are possible.

Clinical Pearls • The GAN consists of contributions from the second and third cervical nerves. The GAN divides into anterior and posterior branches. • The GAN often can be seen both superficial and deep to the sternocleidomastoid muscle within one plane of imaging because the nerve loops around the posterolateral border of this muscle. • Dominance patterns of cutaneous innervation of the external ear have been examined.5 Most patterns are either lesser occipital or great auricular dominant.

References

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1. Thallaj A, Marhofer P, Moriggl B, et al. Great auricular nerve blockade using high resolution ultrasound: a volunteer study. Anaesthesia. 2010;65:836–840. 2. Flores S, Herring AA. Ultrasound-guided greater auricular nerve block for emergency department ear laceration and ear abscess drainage. J Emerg Med. 2016;50(4):651–655. 3. Ritchie MK, Wilson CA, Grose BW, Ranganathan P, Howell SM, Ellison MB. Ultrasound-guided greater auricular nerve block as sole anesthetic for ear surgery. Clin Pract. 2016;6(2):856. 4. Lieba-Samal D, Pivec C, Platzgummer H, et al. High-resolution ultrasound for diagnostic assessment of the great auricular nerve—normal and first pathologic findings. Ultraschall Med. 2015;36(4):342–347. 5. Pantaloni M, Sullivan P. Relevance of the lesser occipital nerve in facial rejuvenation surgery. Plast Reconstr Surg. 2000;105:2594–2599.

Great Auricular Nerve Block

ABSTRACT:

The great auricular nerve is the largest superficial branch of the cervical plexus. It emerges deep to the thin platysma muscle and ascends the neck on the surface of the sternocleidomastoid muscle.

KEYWORDS

auricular innervation patterns sternocleidomastoid muscle lesser occipital nerve

366.e1

Great Auricular Nerve Block

Lesser occipital nerve Great auricular nerve

FIGURE 71.1 Above, left, in 11 of 19 hemifaces (58%), the lesser occipital nerve innervated the superior one-third of the ear. Above, right, in 3 of 19 hemifaces (16%), the great auricular nerve provided sensory supply to the entire ear. Below, left, in 4 of 19 hemifaces (21%), the lesser occipital nerve supplied the superior two-thirds of the ear. Below, right, in 1 of 19 hemifaces (5%), the lesser occipital nerve innervated the majority of the ear, and the great auricular nerve supplied the earlobe. (From Pantaloni M, Sullivan P. Relevance of the lesser occipital nerve in facial rejuvenation surgery. Plast Reconstr Surg. 2000;105(7):2594–2599.)

367

Head and Neck Blocks

Posterolateral

Sternocleidomastoid muscle

A

Great auricular nerve

Anteromedial

368

B

FIGURE 71.2 External photograph showing an out-of-plane approach to great auricular nerve block (A). The corresponding sonogram is shown before needle placement (B).

Great Auricular Nerve Block

Great auricular nerve

Anteromedial

Posterolateral

Sternocleidomastoid muscle

A Great auricular nerve (two branches)

Anteromedial

Posterolateral

Sternocleidomastoid muscle

B FIGURE 71.3 Short-axis view of the great auricular nerve near the posterolateral border of the sternocleidomastoid muscle (A). The great auricular nerve divides into anterior and posterior branches (B).

369

Head and Neck Blocks

Sternocleidomastoid muscle

Anteromedial

Posterolateral

Great auricular nerve

A Internal jugular vein Sternocleidomastoid muscle

Local anesthetic

Carotid artery Great auricular nerve

Anteromedial

Posterolateral

370

B Internal jugular vein

Carotid artery

FIGURE 71.4 Short-axis view of the great auricular nerve before (A) and after (B) injection of local anesthetic. Local anesthetic is seen to distribute around the nerve.

Great Auricular Nerve Block

Posterolateral

Great auricular nerve

Posterolateral

Great auricular nerve

A

B Sternocleidomastoid

371

Sternocleidomastoid

Posterolateral

Great auricular nerve

C Sternocleidomastoid

FIGURE 71.5 The great auricular nerve descends to loop around the posterolateral edge of the sternocleidomastoid muscle, and it therefore can be visible both above and below this muscle within one transverse plane of imaging (A and B, the “double dot” sign). Sliding the transducer caudally verifies that these two nerves join at the muscle border (C, the “boomerang” sign of partial long axis view of the nerve rounding the corner of the sternocleidomastoid muscle). The great auricular nerve can be blocked deep to the sternocleidomastoid muscle for more complete anesthesia.